91Ó°ÊÓ

For each molecule/ion, we will determine the number of bond pairs and lone pairs around the central atom. The sum of these will give the electron domain geometry. a. H2O: Oxygen is the central atom and has 2 bond pairs (to the Hydrogens) and 2 lone pairs. The electron domain geometry is tetrahedral. b. NH3: Nitrogen is the central atom and has 3 bond pairs (to the Hydrogens) and 1 lone pair. The electron domain geometry is tetrahedral. c. NH4+: Nitrogen is the central atom and has 4 bond pairs (to the Hydrogens) and no lone pairs. The electron domain geometry is tetrahedral. d. CH4: Carbon is the central atom and has 4 bond pairs (to the Hydrogens) and no lone pairs. The electron domain geometry is tetrahedral.

Now we will identify the molecular geometry of each molecule/ion using the number of bond pairs and lone pairs. a. H2O: 2 bond pairs and 2 lone pairs – molecular geometry is bent. b. NH3: 3 bond pairs and 1 lone pair – molecular geometry is trigonal pyramidal. c. NH4+: 4 bond pairs and no lone pairs – molecular geometry is tetrahedral. d. CH4: 4 bond pairs and no lone pairs – molecular geometry is tetrahedral.

Finally, we can provide the expected bond angles based on the molecular geometry of each molecule/ion. a. H2O: In a bent molecular geometry, the expected bond angle between the Oxygen atom and the two adjacent Hydrogen atoms is approximately 104.5 degrees. b. NH3: In a trigonal pyramidal molecular geometry, the expected bond angle between the Nitrogen atom and the two adjacent Hydrogen atoms is 107.3 degrees. c. NH4+: In a tetrahedral molecular geometry, the expected bond angle between the Nitrogen atom and the two adjacent Hydrogen atoms is 109.5 degrees. d. CH4: In a tetrahedral molecular geometry, the expected bond angle between the Carbon atom and the two adjacent Hydrogen atoms is 109.5 degrees.